Adnane Reading Log p. 160-165 Blog

Density-dependant limiting factors and density-independent limiting factors are two different types factors. The key words in both these factors are dependant and independent. First, density-dependent limiting factors are biotic whereas density-independent limiting factors are abiotic. This means that density-dependent limiting factors are directly correlated to population related changes such as population size. On the other hand, density-independent limiting factors are not related to population. Another differentiating aspect is the feedback system. Density-dependent limiting factors act as negative feedback because of the fact that they lead back to stability and regulation of the population. In contrast, density-independent limiting factors have no part in a feedback system since they have no effect on population size or density.

The S-curve and the J-curve are both very different and both models of density limiting factors. The S-curve relates to density-dependent limiting factors and the J-curve relates to density-independent factors. The S-curve starts out with exponential growth and then gradually arrives to a constant rate. The J-curve also starts out with exponential growth but unlike the S-curve, it surpasses the carrying capacity and collapses. These collapses are called diebacks. Also, the S-curve is attributed to humans and other large mammals while the J-curve is typically of microbes, fish, and small mammals.

Species are divided into K and r strategists. K and r are variables. K is the carrying out of the environment and r is the rate of population growth. K strategist is the group in which humans are found. Small number of offspring but they take really good care of them, which results in most of them surviving. Also, K strategists tend to stay close to the carrying capacity. In contrast, r-strategists such as fish and other small organisms produce a high amount of offspring but do not take of them and usually leave them behind. These offspring’s usually have a short life span but since the r-strategists’ reproduction is so high and repetitive, they usually exceed the carrying capacity.

 

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